1mep: Difference between revisions

Revision as of 00:56, 3 May 2008

Crystal Structure of Streptavidin Double Mutant S45A/D128A with Biotin: Cooperative Hydrogen-Bond Interactions in the Streptavidin-Biotin System.

OverviewOverview

The thermodynamic and structural cooperativity between the Ser45- and D128-biotin hydrogen bonds was measured by calorimetric and X-ray crystallographic studies of the S45A/D128A double mutant of streptavidin. The double mutant exhibits a binding affinity approximately 2x10(7) times lower than that of wild-type streptavidin at 25 degrees C. The corresponding reduction in binding free energy (DeltaDeltaG) of 10.1 kcal/mol was nearly completely due to binding enthalpy losses at this temperature. The loss of binding affinity is 11-fold greater than that predicted by a linear combination of the single-mutant energetic perturbations (8.7 kcal/mol), indicating that these two mutations interact cooperatively. Crystallographic characterization of the double mutant and comparison with the two single mutant structures suggest that structural rearrangements at the S45 position, when the D128 carboxylate is removed, mask the true energetic contribution of the D128-biotin interaction. Taken together, the thermodynamic and structural analyses support the conclusion that the wild-type hydrogen bond between D128-OD and biotin-N2 is thermodynamically stronger than that between S45-OG and biotin-N1.

About this StructureAbout this Structure

1MEP is a Single protein structure of sequence from Streptomyces avidinii. Full crystallographic information is available from OCA.

ReferenceReference

Cooperative hydrogen bond interactions in the streptavidin-biotin system., Hyre DE, Le Trong I, Merritt EA, Eccleston JF, Green NM, Stenkamp RE, Stayton PS, Protein Sci. 2006 Mar;15(3):459-67. Epub 2006 Feb 1. PMID:16452627 Page seeded by OCA on Sat May 3 00:56:57 2008

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OCA

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- {{Structure
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-|GENE= core streptavidin ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=1895 Streptomyces avidinii])
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-}}
 '''Crystal Structure of Streptavidin Double Mutant S45A/D128A with Biotin: Cooperative Hydrogen-Bond Interactions in the Streptavidin-Biotin System.'''
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 [[Category: Stenkamp, R E.]]
 [[Category: Trong, I Le.]]
-[[Category: biotin-binding protein]]
+[[Category: Biotin-binding protein]]
-[[Category: homotetramer]]
+[[Category: Homotetramer]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May  3 00:56:57 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 22:15:11 2008''